The twenty-first century has been marked by growing integration of technology within commercial buildings and residential homes. Smart homes of this new millennium have independent networks controlling various systems including communications, entertainment, lighting, heating, and security. More homes today are built with expansive great rooms, combination media rooms, cathedral ceilings, large architectural windows and other features that affect the distribution of both natural and electric light. Of particular interest to many architects, developers and builders is chromogenics. Chromogenics is the process by which ‘smart’ windows automatically change from light to dark in response to an environmental condition or in response to an applied voltage, altering the amount of light permitted into a room.
There are several technologies for smart-window applications which may be categorized into two separate categories. The first is “passive” where no electrical charge is needed to alter the amount of light permitted to radiate through the glass. Smart-glass that falls into this category reacts to environmental conditions, wherein the opacity of the glass is altered. Thermotropics and photochromics fall into this category. Thermotropics respond to environmental heating conditions and photocromics darkens in direct response to sunlight. While these technologies are cost efficient, they may not be the most practical applications for smart-glass in commercial or residential buildings.
The second category is “active” where the user controls the opacity of the glass. This category requires an electrical charge to change opacity of the smart-glass. Specifically, these technologies are liquid crystal, suspended particle devices, electrochromics, and reflective hybrids. Liquid crystals respond to an electrical charge by aligning perpendicular to the charged surface, allowing light to pass. When the electrical charge is absent, these liquid crystals become randomly oriented. The disadvantage of liquid crystals is that there are no intermediate light settings, wherein the smart-glass remains either clear or opaque.
Another technology used in a smart-window application utilizes small light-absorbing microscopic particles known as suspended particle devices (SPD). These particles line up in straight lines perpendicular to the conductive layer, enabling light to pass through the smart-glass. Once the voltage is removed, these particles move back into a random pattern. The disadvantage of SPD technology is that the smart-glass must be continually charged in order for the windows to appear transparent. This solution is not the most cost efficient.
Reflective hybrids, however, reflect light as oppose to absorbing light as with the SPD. This type of smart-glass includes a layer of nickel-magnesium alloy sandwiched between two glass panels which may be controlled to switch back and forth between a transparent and reflective state. This type of smart-glass is controlled by a low voltage or injection of hydrogen or oxygen gases.
The most practical and safe technology for smart-glass applications is electrochromic glass. Electrochromic windows darken when a voltage is applied and are transparent when the voltage is removed. Specifically, within electrochromic glass, an electrochromic film layer is applied to an ion conductor which layers on top of an ion storage layer. These three layers are sandwiched between two panels of glass or plastic each coated with a conductive oxide. A control device manually or automatically controls the voltage applied to the conductive oxide. When energized by an electrical current, a chemical reaction begins within the electrochromic film that makes the film change color. The chemical reaction is oxidation reaction wherein molecules of a compound loose an electron. Ions in the sandwiched electrochromic layers enable the material to change from opaque to transparent. The ions allow the electrochromic glass to absorb light. Thus, specifically, when a voltage is applied to the conductive oxide layers formed on the panels of glass, the voltage drives the ions from the ion storage layer through the ion conducting layer and into the electrochromic layer. This reaction effectively enables the electrochromic layer to function as a light valve by changing color when energized by this voltage. As a result, the electrochromic layer becomes opaque and blocks light by darkening when a voltage is applied to the conductive coating on the panels of glass. When the amount of voltage is decreased, the ions are driven out of the electrochromic layer into the ion storage layer. When the ions leave the electrochromic layer, the window lightens and regains its transparency. Once the voltage is removed, the film changes back to a translucent film, effectively allowing the light to pass from one glass panel to the next. An electrochromic smart window only requires electricity to generate the chemical reaction, whereby the window maintains its color without having constant application of a voltage.
More particularly, switchable glazings, more commonly referred to as “E-Glass”, is an emerging category of glass structures having an electrochromic glass that use an electrical voltage to modify the amount of light passing through the glass by adjusting the opacity of the glass. Switchable glazings have applicability for a growing number of product applications including windows, interior partitions, skylights, appliances, instruments, advertising signage and more. In addition, switchable glazings can be used to control light glare and heat entering an office or a home. Interest in switchable glazing technology is influenced by many factors, including a growing movement to offer energy-efficient building solutions, and the emerging desire by users to maintain greater control over their working and living environments.
In particular, smart-glass allows a designer to design a multipurpose room for optimal home theater lighting without incorporating automatic blinds or curtains. Moreover, the glass helps maintain room temperature. Manufacturers also claim acoustic benefits, such as noise reduction, and improved air quality from smart-glass. Specifically, using EGlass, one is able to control the amount of sun entering a room without having to adjust the window-shades. In addition, one is able to obtain privacy without closing the curtains. EGlass eliminates the requirement for mechanical shades, blinds and other window coverings and opens up many design possibilities, particularly for odd shaped and hard-to-reach windows and skylights. A line of revolutionary windows, doors skylights and interior partitions, EGlass products electronically tint, shade and give privacy with the touch of a button.
To provide the feature of dimming the opacity within the smart-glass, one approach may be desirable to adjust the tint using a standard off-the-shelf light dimmer to adjust the voltage applied to the smart-glass. However, the characteristics of a typical dimmer are not directly compatible with the electrical characteristics of a smart-glass device. Several different lighting controls from various sources, including Lutron, have been used to offer discrete dimming of the glass but not full range continuous dimming. Thus, at the present, there are no current products that can offer a full range of dimming for the smart-glass.
A need exists for a lighting control that offers a full range of dimming for smart-glass.
The present invention is directed to overcoming, or at least reducing the effects of one or more of the problems set forth above.